- Last edited 8 months ago ago
DCMI internal peripheral
1 Article purpose
The purpose of this article is to:
- briefly introduce the DCMI peripheral and its main features,
- indicate the peripheral instances assignment at boot time and their assignment at runtime (including whether instances can be allocated to secure contexts),
- list the software frameworks and drivers managing the peripheral,
- explain how to configure the peripheral.
2 Peripheral overview
The DCMI (digital camera memory interface) peripheral is used to receive some video data from an external parallel camera sensor device or any other digital video equipment supporting parallel interface.
The DCMI hardware block can receive raw data frames in RGB565 and YUV422 formats as well as JPEG compressed data.
Refer to the STM32MP15 reference manuals for the complete list of features, and to the software frameworks and drivers, introduced below, to see which features are implemented.
Refer to STM32 DCMI presentation  for an overview of DCMI hardware block and its capabilities.
3 Peripheral usage
This chapter is applicable in the scope of the OpenSTLinux BSP running on the Arm® Cortex®-A processor(s), and the STM32CubeMPU Package running on the Arm® Cortex®-M processor.
3.1 Boot time assignment
The DCMI peripheral is not used at boot time.
3.2 Runtime assignment
3.2.1 On STM32MP15x lines 
Click on the right to expand the legend...
Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:
- ☐ means that the peripheral can be assigned to the given runtime context.
- ☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP15 reference manuals.
|Assignment (single choice)
4 Software frameworks and drivers
Below are listed the software frameworks and drivers managing the DCMI peripheral for the embedded software components listed in the above tables.
5 How to assign and configure the peripheral
The peripheral assignment can be done via the STM32CubeMX graphical tool (and manually completed if needed).
This tool also helps to configure the peripheral:
- partial device trees (pin control and clock tree) generation for the OpenSTLinux software components,
- HAL initialization code generation for the STM32CubeMPU Package.
The configuration is applied by the firmware running in the context in which the peripheral is assigned.
See also additional information in the DCMI device tree configuration article for Linux®.
6 How to go further
Refer to STM32 DCMI Application Note (AN5020) for a detailed description of the DCMI peripheral and applicable use-cases.
This application note is related to STM32 microcontrollers but it is also applicable to STM32 MPUs. This document can help to better understand stm32-dcmi V4L2 kernel driver and debug camera sensor and DCMI interactions.